my car all of a sudden, it seemed, would choke and die anytime i was in drive with the accelerator depressed (stop lights, drive thrus). took it to the local shop and they replaced the catalytic converter, with both sensors. they gave me the car back and the moment i started it the rpms starting running wild, jumping from 2.5 to 1000. the car runs ok except it gains speed while coasting (I've gotten it up to 31 mphs without touching the gas!) took it back to the shop and they replaced the throttle body, costing me more and fixing nothing. please help.